Ear pads



April 16, 1963 R. E. ULRICH ETAL.

EAR PADS Filed July 20, 1959 IN V EN TOR! foaizr 5. Z/M/m EVA-i577 ,8 mm

United States Patent 3,085,253 EAR PADS Robert E. Ulrich, Riverton, and Everett R. Ware, Pennsauken, N..li., assignors to Radio Corporation of Amerion, a corporation of Delaware Filed July 20, 1959, er. No. 828,389 5 Claims. (til. 2-409) This invention relates generally to devices for protecting the ears of a person from noise, and more particularly to improved, noise attenuating ear pads of the type adapted to be disposed between the rigid ear cups of a noise protective device and the head of a person. The ear pads of the present invention are especially useful for personnel located in the vicinity of loud, ambient noises.

Discomfort and even loss of hearing have been induced in people by ambient noise levels approaching 100 decibels, and higher. Thus, the possibility of damaging their hearing presents a serious problem to all personnel who must work near high level noise operations. It has been proposed to attenuate ambient noises by providing personnel with car cups having ear pads of soft rubber, or of a plastic sheath filled with a liquid. While these prior art devices have been useful in attenuating ambient noises appreciably and in relieving discomfort, it is desired to attenuate ambient noises still further than the attenuation afforded by the prior art pads.

In cases where liquid-filled ear pads of a plasticized plastic material have been used, it has been found that the hair and body oils of a user remove the plasticizerfrom the plastic. orate, so that their usefulness is relatively short lived. In many such cases, especially where water has been used as part of the liquid filler within the ear pads, it is found that the liquid eventually evaporates through the plastic which has been affected.

Accordingly, it is an object of the present invention to provide improved ear pads for use with noise protective devices to attenuate ambient noise and which are relatively free from the aforementioned and other disadvantages of previously known ear pads.

It is a further object of the present invention to provide improved ear pads that have superior noise attenuating properties over ear pads of the prior art, and that resist deterioration With prolonged use.

Still a further object of the present invention is to provide improved ear pads having a filler that will remain operable and maintain its physical pliant state over a wide range of temperatures, and efiiciently attenuate noise.

it is another object of the present invention to provide improved, detachable, noise attenuating, ear pads that are relatively simple in structure, are easy to manufacture, and are highly efficient in use.

in accordance with the present invention, the improved ear pads comprise tube-like sheaths of a plasticized plastic, each sheath being preferably partially collapsed and filled with a filler of grease-like consistency. The filler in our preferred embodiment comprises a mixture of a grease and a plasticizer similar to the plasticizer in the plastic sheath. The ear pad is formed with a peripheral, inwardly extending flap that is adapted to engage a flange at the rim of a rigid ear cup for attachment thereto. The plasticizer in the mixture within the sheath of the ear pad serves to replace any plasticizer that is removed from the plastic sheath by the hair and body oils of the person wearing the ear protective device. Deterioration of the ear pads is thus greatly retarded.

The novel features of the present invention, both as to its organization and method of operation, as well as additional objects and advantages thereof, will be understood The plastic pads then readily deteri- 3,d35,253 Patented Apr. 16, 1963 "ice more readily from the following description, when read in connection with the accompanying drawings in which similar reference characters designate similar parts, and in which:

FIG. 1 is a perspective view of an ear protective device employing improved ear pads according to the present invention; and

FIG. 2 is a cross-sectional view taken along the line 2-2 in FIG. I, viewed in the direction indicated by the arrows, and showing the internal structure of one of the ear pads of FIG. 1.

Referring, now, to FIG. 1, there is shown a noise protective device .10 having a pair of similar, rigid, circumaural, ear cups 12 and 14 of plastic or other suitable material. Each of the ear cups 12 and 14 is mounted on a separate one of the two ends of a headband 16. The headband 16 comprises two generally parallelly disposed, resilient wires '18 and 20 held in substantially parallel alignment by a strip 22 of flexible material, such as rubher or plastic.

The rigid ear cups 12 and 14 are both formed, on the front portions thereof, with two laterally extending, aperturecl ears 24 and 26. The wire 18 extends at both ends thereof through the apertures of the respective pairs of ears 2'4 and 25. A bead 28 is fixed to each end of the wire 18 below the ear 26 and two heads 30' are fixed to the wire 18, each above a different one of the ears 24. A bead 32 is slidably and frictionally mounted on the wire :18 between each pair of the ears 24 and 26. The Wire 20 is slidably connected to the rear portions of the ear cups 12 and '14 in the same manner as described for the wire 18. It will be seen that the ear cups 12 and 14 may be slidably adjusted with respect to the headband 16 so as to dispose them around the ears and resiliently against the head of a wearer. Since the ear cups 12 and 14 and the ear pad for each are similar, only the ear cup 12 and its associated ear pad 36'will be described hereinafter in greater detail.

The ear cup 12 is generally cup-shaped and large enough to fit around the ear of a person. The rim of the ear cup 12 is formed with a relatively wide, marginal flange 34 for a purpose hereinafter appearing. A liner 35 of sound absorbing material, such as isocyanate foam, may be disposed within the ear cup 12, as shown.

An improved ear pad 36 according to the present invention is mounted on the flange 34 of the ear cup 12 for disposition between the flange 34 and the head of a wearer.

The ear pad 36 comprises a tube-like sheath of pliable material having the general shape of the flange 34 forming the rim of the ear cup 12. The ear pad 36 is formed with a peripheral, inwardly extending flap 38 which embraces the flange 34 for attaching the pad to the ear cup 12. With this arrangement, the ear pad 36 may be easily removed from the ear cup 12, if necessary. The flange 34 fits between the flap 38 and the ear pad 36. The sheath 40 of the ear pad 36 should be made from a material that has the property of remaining pliable over a long period of time.

A polyvinylchloride plastic which is plasticized with a plasticizer of di 2-ethyl hexyl phthalate, hereinafter referred to as DOP, a trade name commonly used in the plastic industry for this plasticizer, has been found to be satisfactory. It will be understood, however, that other materials and softeners therefor may be used within the purview of this invention.

Superior noise attenuating characteristics for the ear pad are obtained by filling the pad, preferably while in a partially collapsed state, with a filler comprising a grease having the characteristics set out in this specification, or with a mixture of said grease and a plasticizer.

The completely filled, partially collapsed sheath is then sealed, as by heat or cement. As an example, the grease in the filler 42 may comprise petroleum jelly alone, or a mixture of petroleum jelly and parafiin wax. An ear pad 36 of polyvinylchloride plastic (Formula 2951 of the Bakelite Corporation, for example), 0.012" thick, containing in the order of 38.26% DOP as a plasticizer, by weight, and filled with a filler of 23.8% DOP, 28.5% petroleum jelly, and 47.7% paraffin wax, by weight, has been found to possess superior noise attenuating properties and a prolonged useful life.

In use, the resilient headband 16 urges the ear pad 36 against the side of the head around the ear. The filler 42 of the ear pad 36, being of grease-like consistency over a wide range of temperatures, will very quickly conform to the contour of the wearers head. Body and hair oils of the wearer, however, have a tendency to remove the plasticizer from the plastic sheath 40. Unless this plasticizer, or some other suitable softener is replaced in the sheath 40, the plastic sheath will deteriorate. The plasticizer, DOP, in the filler 42 within the sheath 40, serves to replace the plasticizer removed from the sheath 40 by the wearer. By the use of proper quantities, such as in the example given, supra, an equilibrium may be maintained between the amount of plasticizer extracted from the plastic sheath 40 by the wearer and the amount of plasticizer donated to the plastic sheath 40 by the plasticizer in the grease-like mixture. Under these conditions, the ear pad 36 may be considered to be equalized.

A filler of grease-like consistency for the plastic sheath 40, has been found to be superior to liquid fillers from the standpoint of attenuating ambient noise. By the terms grease or filler of grease-like consistency is meant a filler that will not flow easily due to its own weight. For the purposes of the present invention, greases having a viscosity within the range of 500 to 10,000 centipoises may be used as a filling medium.

From the foregoing description, it will be apparent that there have been described improved, circumaural, ear pads for a device for protecting personnel from noise. While only a few improved, equalized, ear pads have been described, other equalized ear pads will, no doubt, readily suggest themselves to those skilled in the art. The filler of grease-like consistency described herein will retain its pliant physical state over relatively wide ranges of temperatures, on either side of normal room tempera ture, thereby being suitable for ear pads for plane and helicopter personnel. The ear pads of the present invention may also be used, in a smaller size, as direct-aural noise attenuators, that is, directly in contact with the human ear. Since many variations are possible within the spirit of the this invention, it is desired that the foregoing shall be considered merely as illustrative and not in a limiting sense.

What is claimed is:

l. A pad comprising a sealed tube-like sheath of plasticized plastic, said sheath being filled with a mixture comprising a filler of grease and a plasticizer for said plastic.

2. A pad comprising a tube-like sheath of a plastic plasticized with d-i 2-ethyl hexyl phthalate, said sheath being filled with a mixture comprising a grease and di Z-ethyl hexyl phthalate.

3. A pad as defined in claim 1 wherein said grease comprises petroleum jelly and parafiin wax, and said plastic sheath comprises polyvinylchloride.

4. An ear pad adapted for use between the rim of an ear cup and the head of a person, said ear pad comprising a tube-like sheath of polyvinylchloride plastic having the general shape of said rim and plasticized with di Z-ethyl hexyl phthalate, and said tube being partially collapsed and completely filled with a mixture of greaselike consistency comprising a grease and di 2-ethyl hexyl phthalate.

5. An ear pad adapted for use between the rim of an ear cup and the head of a person, said ear pad comprising a tube-likesheath of polyvinylchloride plastic having the general shape of said rim and plasticized with di Z-ethyl hexyl phthalate, and said tube being partially collapsed and a filler for said tube comprising a mixture of greaselike consistency comprising a grease and di Z-ethyl hexyl phthalate, said mixture having a viscosity within the range of 500 and 10,000 centipoises.

References Cited in the file of this patent UNITED STATES PATENTS 707,550 Chin-mock Aug. 26, 1902 2,094,534 Halle Sept. 28, 1937 2,262,568 Wade Nov. 11, 1941 2,653,601 Morrison Sept. 29, 1953 2,801,423 Shaw et a1. Aug. 6, 1957 2,990,553 Ulrich et a1 July 4, 1961 

1. A PAD COMPRISING A SEALED TUBE-LIKE SHEATH OF PLASTICIZED PLASTIC, SAID SHEATH BEING FILLED WITH A MIXTURE COMPRISING A FILLER OF GREASE AND A PLASTICIZER FOR SAID PLASTIC. 